The present invention generally relates to implants adapted for use in attaching a prosthesis to a bone.
It is well known to provide implants with screw threaded sections intended to retain an implant within a preformed hole provided in a bone; and to form such implants from a bio-compatible material intended to provide for healing osseointegration subsequent to implantation. Titanium is a particularly desirable implant material in that titanium oxide is capable of providing for an intimate bond or joint with bone matter incident to healing of the bone following implantation. It is desirable to pretreat the implant with a view towards increasing the rate of oxide formation, which otherwise occurs naturally to titanium in the presence of organic materials.
Heretofore, it has been common practice to provide implants with self-tapping screw threads with a view towards supplementing the holding power of the implant otherwise obtained from the growth of bone into cutting/locking recesses extending lengthwise of the threaded section of the implant, such as is disclosed for instance in U.S. Pat. No. 4,324,550.
Implants employing conventional screw threads often must be replaced, due to the shear failure of portions of bone engaged by the implant and/or due to failure of the bone to grow into uniform intimate contact with the implant adjacent areas where surface discontinuities are present in the preformed hole formed in the bone and/or the implant.